1. Technical Field
The present invention relates to a device for testing a product using communication ports of a personal computer and, more particularly, to a device for testing a product using communication ports of a personal computer capable of insuring efficiency in testing the product by providing an interface between a programmable logic controller and the personal computer through either serial communication port(s) or parallel communication port(s) of the personal computer.
2. Related Art
Recently, in order to ensure objectivity and reliability in testing products in a manufacturing line, the efficiency and quality of the product is measured and tested to sort inferior goods by connecting a test instrument and a testing object to a personal computer (PC). Control values of each compartment of the product to be tested are adjusted so as to comply with normal values. Specifically, when testing the product, a programmable logic controller (PLC) loads/unloads a mechanical part of the product by receiving a command supplied by the personal computer in order to broad-based automation.
The PLC is a control device equipped with programmable logic which can prepare a test environment capable of easily measuring, controlling and/or detecting errors regarding an actual test target by receiving a test condition or a command which is supplied from the outside by an operator or the personal computer in testing the product. For example, in a continuous operation for testing the test target product using a conveyer system, the PLC regularly positions the mechanical part of the test target product to be tested, and loads the mechanical part so that the test instrument connected to the PC can perform the relevant test precisely and properly test measuring items. After the test is completed, the PLC unloads the test target product whose test is completed so as to load automatically a mechanical part of a next test target product to be tested.
When using the above PLC, the operation of manually loading or unloading the test target product as performed manually by the operator, is excluded and unmanned automation is realized, thereby maximizing working efficiency.
In order to exchange control authority between the PC and PLC, it is essential to establish mutual interface between them. To interface between the PC and PLC, a communication unit is used.
However, as unmanned automation is realized by using a PLC which is dependent upon the interface by the communication unit, there is an economic burden in manufacturing the control device, such as the PLC, for controlling the mechanical part of the product. The control device for controlling the mechanical part of the product using a communication unit is different from other equipment which do not use the communication unit. Moreover, as the communication unit is used, the programs for measuring, controlling and testing as used in the PC, and the program of the PLC, should be corrected. In the case where a communication unit is not used, since the interface is not set between the PC and the PLC, unmanned automation is not realized.
The following patents are considered to be representative of the prior art relative to the use of programmable logic controllers, but are burdened by the disadvantages set forth herein: U.S. Pat. No. 4,078,259 to Soulsby et al., entitled Programmable Controller Having A System For Monitoring The Logic Conditions At External Locations, U.S. Pat. No. 4,807,161 to Comfort et al., entitled Automatic Test Equipment, U.S. Pat. No. 5,131,092 to Sackmann et al., entitled Communication System Enabling Programmable Logic Controllers Access To Host Computer Tasks And Host Computer Access To Programmable Logic Controllers Without Polling, U.S. Pat. No. 5,220,522 to Wilson et al., entitled Peripheral Data Acquisition, Monitor, And Control Device For A Personal Computer, U.S. Pat. No. 5,245,704 to Weber et al., entitled System For Sharing Data Between Microprocessor Based Devices, U.S. Pat. No. 5,251,302 to Weigl et al., entitled Network Interface Board Having Memory Mapped Mailbox Registers Including Alarm Registers For Storing Prioritized Alarm Messages From Programmable Logic Controllers, U.S. Pat. No. 5,307,463 to Hyatt et al., entitled Programmable Controller Communication Module, and U.S. Pat. No. 5,485,590 to Hyatt et al., entitled Programmable Controller Interface Module Which Is Configurable By A Removable Memory Cartridge.